Fault location in radial and meshed networks containing distributed energy resources (DERs) and high-voltage direct current (HVDC) lines

Abstract

Renewable energy provided by rapidly increasing numbers of Distributed Energy Resources (DERs) connected to transmission and distribution networks via Inverter Based Power Sources (IBPSs) introduce new challenges in detecting and locating faults. Distribution networks are historically designed to operate as radial systems with unidirectional power flows, which may no longer hold true due to the presence of large numbers of IBPSs. The commonly used impedance-based fault location methods are no longer reliable due to the limitations imposed by asymmetry of lines and presence of IBPSs, which need to comply with the new grid codes for Fault Ride Through (FRT) requirements. In this dissertation, a new fault location method which can be used for radial and meshed networks containing DERs and can address the limitations of conventional methods mentioned above will be introduced. The approach requires a limited number of digital fault recorders (DFR) to be placed in the network and uses the Discrete Wavelet Transform (DWT) to compute the first arrival times of fault-generated traveling waves. The dissertation first introduces a new two-terminal fault location technique used strictly for radial distribution networks and then extends this to the general case of combined transmission and distribution networks with radial or meshed configurations. The method is further extended to be applied to hybrid AC/DC complex transmission grids containing DERs and High-Voltage Direct Current (HVDC) lines. AC and DC complex radial and meshed networks are used to validate the fault location performance of proposed algorithms under different fault types and conditions. --Author's abstract